1. Field of the Invention
The present invention relates to a construction machine, such as a hydraulic shovel, provided with an engine room.
2. Description of the Background Art
Conventionally, there has been known a hydraulic shovel, as a construction machine provided with an engine room, as disclosed in Japanese Unexamined Patent Publication No. 2004-353539 or Japanese Unexamined Patent Publication No. 2008-8257. FIG. 8 shows an overall construction of a general hydraulic shovel, and FIG. 9 shows an example of disposition of various devices provided in an engine room of the hydraulic shovel.
The hydraulic shovel shown in FIG. 8 includes a base carrier 1 having right and left crawlers, an upper slewing structure 2 to be loaded on the base carrier 1 to be slewed around an axis perpendicular to the ground, and a working attachment 3 to be attached to the upper slewing structure 2. An engine guard 4 is provided at a rear part of the upper slewing structure 2, surrounding an engine room 5.
As shown in FIG. 9, the engine room 5 is internally provided with an engine 6, a heat exchanger 7 such as a radiator, a cooling fan 8, a hydraulic pump 9, an exhaust muffler 10, and unillustrated engine-related devices. The heat exchanger 7 and the cooling fan 8 are disposed on one side of the engine 6 side by side (right and left directions when viewed from the rear side of the construction machine: the definition is the same for the following description). The hydraulic pump 9 is disposed on the other side of the engine 6, and the exhaust muffler 10 is disposed above the hydraulic pump 9 at a position higher than the engine 6.
The engine guard 4 includes an upper side wall portion, which is comprised of right and left fixed hoods 12 and 13, a bonnet 11, and other panel members. The fixed hoods 12 and 13 are spaced in right and left directions, positioned at opposite sides of an opening formed in a center region of the engine guard 4. The bonnet 11 is provided so as to open/close the opening, having a shape of protruding upward beyond the fixed hoods 12 and 13 when closing the opening.
The upper side wall portion of the engine guard 4 is formed with a suction port 14, a first exhaust port 15 and a second exhaust port 16, the exhaust ports 15 and 16 positioned on the opposite side of the suction port 14. The cooling fan 8 is rotated to thereby suck the air outside the engine room 5 into the engine room 5 through the suction port 14, and discharge the air to the outside of the engine room 5 through the first and the second exhaust ports 15 and 16 so as to lead the air to pass through around the heat exchanger 7 and the engine 6. This forms an air flow for cooling the heat exchanger 7, the engine 6, and peripheries thereof.
The suction port 14 is formed in the fixed hood 12, located on the left side in FIG. 9, that is, on the windward side of the cooling fan 8. The first exhaust port 15 is formed below a leeward end of the bonnet 11, opened in a direction parallel to the axial direction, namely, horizontal direction, of an engine output shaft 6a so as to allow the air that has cooled the heat exchanger 7 to be mainly discharged through the first exhaust port 15. The second exhaust port 16 is formed in the leeward-side fixed hood 13 so as to be opened upward on the leeward side of the first exhaust port 15 and at a position lower than the first exhaust port 15, letting the air that has passed around the engine 6 and the hydraulic pump 9 so as to vertically pass through the engine room 5 be discharged through the second exhaust port 16. The exhaust muffler 10 is disposed at a position closer to the second exhaust port 16 than the engine 6.
The engine guard 4 is further provided with a guide member 17. The guide member 17 is attached to the bonnet 11 at a position lower than the bonnet 11 so as to be opened/closed integrally with the bonnet 11, positioned in a horizontal posture on the windward side of the leeward-side fixed hood 13 when the bonnet 11 is closed. The guide member 17 defines an exhaust passage 18 with the bonnet 11 therebetween. The exhaust passage 18 mainly guides the air that has passed through the heat exchanger 7 to the first exhaust port 15.
In the conventional construction machine, however, the first exhaust port 15 and the second exhaust port 16, being formed in proximity to each other on the leeward side of the cooling fan 8 as shown in FIG. 10, cause an exhaust air flowing in a lateral direction through the first exhaust port 15 and an exhaust air flowing upward through the second exhaust port 16 to collide against each other. This may deteriorate the air flows through the first and the second exhaust ports 15 and 16, thus lowering the cooling flow rate and deteriorating the cooling performance. Furthermore, the horizontally opened first exhaust port 15 allows noise e.g. engine sounds to be output through the first exhaust port 15 approximately with no constraints, thus causing noise at lateral sides of the construction machine to be increased.